<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>04_JS流程控制</title>
</head>
<body>
  <script>
      //1.顺序结构
      console.log('1');
      console.log('2');
      console.log('3');

      //2.分支结构
      let uname='tom';
      if(!uname){
        alert('请先登录！')
      }else {
        alert('欢迎'+uname+'回归！');
      }

      //3.选择分支
      let gender=30;
      switch (gender){
        case 1:
          console.log('男');
          break;
        case 0:
          console.log('女');
          break;
        default:
          console.log('未知');
      }

      //4.循环结构
      let name=['ys','ysyyds','ys666'];
      for(var i=0;i<name.length;i++){
        console.log(name[i]);
      }
      //如果用var定义循环变量i,循环结束后在此处仍能打印出i的值
      // 但如果用let定义,就会报错,变量i不存在!
      console.log(i);

      //5.增强for循环
      //n是每轮循环取出的内容 names是被遍历的数组
      for(let n of names){
        console.log(n);
      }








  </script>
</body>
</html>